Dose Reduction in Pediatric Molecular Imaging Project Summary The radiation exposure resulting from medical imaging has become a public safety concern. Nuclear medicine imaging provides potentially life-saving information regarding physiological processes. Such imaging is particularly valuable in children and infants wherein the rapid and unequivocal diagnosis of developmental or pathological concerns is essential for the health of these patients. Our overall objective is to reduce pediatric patient absorbed dose while maintaining and even improving the diagnostic quality of nuclear medicine images. Dose reduction for pediatric patients is particularly important since such patients are at increased risk owing to the enhanced radiosensitivity of their tissues and the longer time-period over which stochastic radiation effects may manifest. We will accomplish this overall objective by: 1. Optimizing image acquisition, reconstruction, and processing methods to achieve the best image quality at the lowest possible administered activity; 2. Collecting imaging-based pharmacokinetic data for agents commonly used in pediatric patients; 3. We will develop online tools that compare dose and image quality for patients of different weights and heights at different administered activities with dose and image quality metrics obtained using the current consensus guidelines and; 4., investigate the sensitivity of the results obtained in aims 1 and 3 to changes in instrumentation. Collectively, these aims will substantially impact dosing of pediatric patients for molecular imaging procedures. Aims 1 and 2 will provide the data needed to evaluate whether consensus guidelines lead to dose reduction for all pediatric patients. We already demonstrated in the prior grant period that optimal dose reduction (i.e., reduction that preserves diagnostic image quality) requires an accounting of both patient height and weight. Aim 3 will provide the tools to enable professional organizations to rigorously evaluate and likely refine or provide alternatives to consensus dose guidelines. Any guideline or dose- reduction effort that endeavors to maintain diagnostic image quality will be susceptible to imaging instrumentation variability. In Aim 4, we examine the impact of this variability on both already established consensus guidelines and also on the optimization scheme that we propose to develop via aims 1-3. By using state-of-the-art computational simulation, image quality evaluation, and radiation dosimetry tools (many of which were developed by the investigators), the work proposed in this grant application will apply dose reduction methods in a much more rigorous and scientifically validated manner. We expect that completion of the proposed studies will allow the molecular imaging community to introduce and, consistent with the realities of clinical practice, implement pediatric dose-reduction approaches that substantially improve upon current guidelines and that also point to future technological advances that could yield even greater dose-reduction while simultaneously improving diagnostic image quality.